This study will inform the cancer registry community of when it is appropriate to supplement cancer registry data with external sources, and what data items are amenable to being supplemented without bias in the resulting statistics. Misclassification bias will be evaluated to check the robustness of the SEER statistics. Objectives: 1) Evaluate the feasibility of supplementing specific selected cancer registry variables (race-ethnicity, birthplace, treatment, tumor biomarkers) with data from 3 defined sources: a) patient interview research studies, b) POC, and c) electronic health records (HER) data. 2) Evaluate the potential for improving SEER-based standard cancer reporting statistics (e.g., incidence, prevalence, treatment-specific survival) by augmenting race/ethnicity, birthplace, treatment, and tumor biomarkers registry data with supplementary data.